1. Field of the Invention
This invention relates to actuator systems and magnetomechanical cantilever beams used therein, and more particularly to a magnetomechanical cantilever beam that enhances the versatility of the actuator system.
2. Description of the Prior Art
Actuators of the type upon which this invention has improved are conventionally employed as indirectly activated driving mechanisms providing repetitive displacements of desired force and magnitude. Two main classes of such actuator systems presently include mechanically activated cam follower systems and electronically activated solenoid plunger systems.
A cam is usually a plate or cylinder which communicates motion to a follower by means of its edge or a groove cut in its surface. In the practical design of cams the follower (1) must assume a definite series of positions while the driver occupies a corresponding series of positions or (2) must arrive at a definite location by the time the driver arrives at a particular position. The former design is severely limited in speed because the interrelationship between the follower and cam positions yields a follower displacement versus time function that involves large values for the successive time derivatives, indicating large accelerations and forces and large impacts and noise. The second design requires the determination of that particular interrelationship between the follower and cam positions which results in minimum forces and impacts, so that the speed may be increased. In the case of high speed machines, small irregularities in the cam surface or geometry may be severely detrimental. Thus cam and follower systems have two major drawbacks, they produce relatively slow motions and they have minimal versatility resulting from their need to be mechanically activated.
A solenoid and plunger system is a helically wound insulated conductor (solenoid) provided with a movable iron rod or bar (plunger). When the coil is energized, the iron rod becomes magnetized and the mutual action of the field in the solenoid on the poles of the plunger causes the plunger to move within the solenoid. This force becomes zero when the magnetic centers of the plunger and solenoid coincide. When a load is attached to the plunger, work will be done until the force to be overcome is equal to the force that the solenoid exerts on the plunger. The force usually increases very sharply near the final seating point of the plunger and care must be taken that sufficient excess force is available throughout the stroke to prevent stalling of the motion. The duty cycle of solenoids is often limited to the classifications of continuous and intermittent. The main limitation in duty cycles is the amount of resistive heating that can be tolerated by the solenoid without damage to itself or its surroundings during its operating cycle. Force availability drops off rapidly with rising coil temperature. The larger the required force, the larger the solenoid and plunger must become to decrease the resistive heating which, in turn, increases the system's time response. As a result, solenoid and plunger systems typically have a large size-to-force ratio and are relatively inefficient owing to their method of magnetic to mechanical energy transfer.